Description
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Trees , to 30 m; crowns oblong. Bark gray, deeply fissured with broad, flattened ridges. Wood hard. Branches short-spreading, young branches pubescent, old-growth with 3-5 prominent, irregular, corky wings; twigs reddish, pubescent. Buds brown, ovoid, acute, pubescent; scales brown, pilose on outer surface, ciliate on margins. Leaves: petiole ca. 5 mm, pubescent. Leaf blade obovate to oblong-oval, (2.5-)9-11(-16) × 2.5-5 cm, base oblique, margins doubly serrate, apex short-acuminate; surfaces abaxially white-pubescent, pubescence not tufted in axils of veins, adaxially dark green, usually glabrous, sometimes scabrous. Inflorescences racemose cymes, long-pendulous, (7-)10(-13)-flowered, to 5 cm; pedicel 0.5-1 cm. Flowers: calyx deeply lobed, divided nearly to middle, lobes 7-8; stamens 5-8; anthers dark purple; stigmas greenish, pubescent. Samaras elliptic to oval, 1.5-2.2 cm, narrowly winged, pubescent, margins short-ciliate, apex shallowly notched. Seeds inflated, not thickened. 2 n = 28.
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Distribution
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Ont.; Ark., Ill., Ind., Iowa, Kans., Ky., Mich., Minn., Mo., Nebr., N.H., N.J., N.Y., Ohio, S.Dak., Tenn., Vt., W.Va., Wis.
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Flowering/Fruiting
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Flowering spring.
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Habitat
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Rocky slopes, limestone outcrops, rich woods, flood plains, stream banks; 30-900m.
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Synonym
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Ulmus racemosa Thomas 1831, not Borkhausen 1800
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Associated Forest Cover
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Rock elm is a minor component in two forest cover types: Sugar
Maple-Beech-Yellow Birch (Society of American Foresters Type 25)
and Black Ash-American Elm-Red Maple (Type 39). In addition to
type species, other important associates include white ash (Fraxinus
americana), black cherry (Prunus serotina), basswood
(Tilia spp.), northern red oak (Quercus
rubra), American elm (Ulmus americana), eastern
hophornbeam (Ostrya virginiana), and eastern hemlock (Tsuga
canadensis).
Some of the woody shrubs commonly associated with rock elm include
prickly ash (Zanthoxylum americanum), beaked hazel (Corylus
cornuta), blackberry and raspberry (Rubus spp.),
dogwoods (Cornus spp.), gooseberry (Ribes
spp.), Atlantic leatherwood (Dirca palustris), bittersweet
(Celastrus scandens), Virginia creeper (Parthenocissus
quinquefolia), grape (Vitis spp.), hawthorn
(Crataegus spp.), American and redberry elder
(Sambucus canadensis and S. pubens), and
nannyberry (Viburnum lentago).
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Climate
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The climatic conditions associated with the distribution of rock
elm can be characterized as continental, with cold winters and
warm summers. Within the species range, a maximum summer
temperature of 38° C (100° F) and a minimum winter
temperature of -34° C (-30° F) are common.
Annual precipitation is 640 mm (25 in) in the western part of the
range and 1270 mm (50 in) in the extreme southern and eastern
parts. At least half of this precipitation occurs during the
growing season. Snowfall averages from 50 to 200 cm (20 to 80
in), depending on geographic location.
The frost-free period averages 100 days in the north and 200 days
in the south. Rock elm grows best where the frost-free period is
from 120 to 160 days.
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Damaging Agents
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Nearly all native North American elm
species are susceptible to Dutch elm disease (Ceratocystis
ulmi) (6,13) and isolates of C. ulmi have been
obtained from rock elm logs (5). It is likely that Dutch elm
disease will greatly reduce the number of rock elm..
A seed-borne fungus (Gleosporium ulmicolum) has been
reported for rock elm but few of the fungi that are able to
invade the fruits and seeds of North American hardwoods are
thought to be pathogens that reduce germination or weaken
seedlings (1).
Although rock elm has not been listed as a particular host for
specific insects, undoubtedly it is host to the various borers,
defoliators, and sucking insects that attack American elm.
Throughout the range of rock elm, killing frosts are common during
the flowering period and subfreezing temperatures may prevent
seed development in some years.
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Flowering and Fruiting
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Rock elm flowers appear 2 weeks
before the leaves at any time from March to May, depending on
locality and site. The perfect flowers are protandrous, that is,
the male elements of the flower develop 2 to 4 days before the
female elements are receptive (6). Female flowers are receptive
for only a few days.
The hairy fruit has a broad wing from 13 to 25 mm (0.5 to 1 in)
long and matures during May or June. Clean, fully ripened,
unwinged seeds number from 11,000 to 19,800/kg (5,000 to
9,000/lb). Seeds germinate soon after they ripen.
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Genetics
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In a study of compatibility and crossability in Ulmus
(11), the form of dichogamy (protandry or protogyny) correlated
with the compatibility between the different species. Ulmus
thomasii is a protandry species and is compatible with two
other protandry species-U. pumila and U. laevis.
Ulmus thomasii is also self-fertile.
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Growth and Yield
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Few species have rock elm's capacity for
recovering from prolonged suppression. An analysis of 153 trees
indicated that a large percentage had survived under suppression
for 50 years or more. This capacity makes it difficult to
correlate diameter and age (9):
Crown
class
D.b.h. class
Dominant
Codominant
Intermediate
Suppressed
2.5 cm or 1 in
14
22
30
48
7.6 cm or 3 in
26
50
64
99
12.7 cm or 5 in
39
72
97
--
17.8 cm or 7 in
51
93
--
--
22.9 cm or 9 in
63
--
--
--
The average number of rings per 2.5 cm (1 in) of radius by crown
class was about 50 for suppressed, 30 to 40 for intermediate, 20
to 30 for codominants, and 10 to 20 for dominants.
On average to better sites, mature rock elm may reach 27 in (90
ft) in total height and 61 cm (24 in) in d.b.h. (12). In virgin
hardwood stands in the east and north, 27 to 30 in (90 to 100 ft)
heights and 91 to 152 cm (36 to 60 in) in d.b.h. have been
recorded (10). Much smaller trees occur along river bluffs, on
limestone outcrops, or other sites with thin soil mantles. Rock
elm may live 250 to 300 years.
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Reaction to Competition
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Rock elm is considered shade
tolerant in the seedling-sapling stage and often recovers
successfully after long periods of suppression at these stages.
As the tree grows older, however, it apparently becomes more
light demanding. Overall, the species is classed as intermediate
in tolerance to shade (10).
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Rooting Habit
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No information available.
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Seed Production and Dissemination
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Trees 20 years old
produce viable seeds, but maximum yields are from trees 45 to 125
years old. Good crops occur every 3 or 4 years. Ripe seeds are
dispersed as the leaves become fully expanded, which is usually 2
or 3 weeks later than the time of seed drop for American elm (9).
Although the thin, hair-fringed, winged samaras seem adapted to
wind dispersal, seeds are generally carried no more than 40 to 45
m (100 to 150 ft) from the parent tree. The fact that rock elm
grows as scattered individuals, often several miles from the
nearest seed source, suggests that birds and small mammals play a
role in dissemination. The large but very light seeds are also
buoyant and water can carry them long distances. As a result,
seeds often are concentrated along the banks of streams and
lakes.
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Seedling Development
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Rock elm seeds germinate within a
week or two after dispersal if moisture conditions are favorable.
In a germination test, 90 to 100 percent of mature seeds were
viable (2). Viability was not significantly different between
seeds from different trees, between seeds with wings or without
wings, or between seeds with seed coats or without seed coats.
When germinated in a petri dish, radicles of the viable seeds
emerged within 2 or 3 days and were 2.5 to 3.8 cm (1 to 1.5 in)
long by the end of the fifth day Germination is epigeal. The
cotyledons began to open about the fifth or sixth day. Under
favorable conditions, rock elm seedlings are from 5 to 8 cm (2 to
3 in) tall by the end of the first summer.
Despite its high seed viability, rock elm regenerates poorly
(2,9). Germination tests failed when mineral soil and equal
volumes of peat moss, sand, and mineral soil were used for
planting media, but 70 to 80 percent emergence was obtained in
flats using peat moss. Another factor affecting seedling
establishment is the persistence of dormant terminal buds.
Emergent seedlings rarely develop more than a single pair of true
leaves during the first growing season due to this dormancy.
Observations on more than 200 seedlings indicated that only 1
percent broke dormancy long enough to develop an additional
internode and a second pair of true leaves.
This species appears to be shade tolerant during the seedling
stage (10). However, under field conditions with competition,
1.5-0 nursery stock averaged only 27 cm (10.6 in) in height 5
years after planting and only 52 cm (20.4 in) 10 years after
planting in northern Wisconsin. In the same study, survival
ranged from 85 percent at the end of the 1st year to 32 percent
at the end of the 10th year.
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Soils and Topography
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Rock elm is most frequent in lower Michigan, Wisconsin, and
southern Ontario, and it is regularly found on moist but
well-drained sandy loam, loam, or silt loam soils in mixture with
other hardwoods. In Wisconsin, rock elm is most frequent in the
southern wet-mesic forest (7). Although rock elm often grows on
rocky ridges, limestone outcroppings, and streambanks, the
highest quality sawtimber is found on deeper loamy soils.
The major soil orders associated with the distribution of rock elm
are the Mollisols, Alfisols, and the Spodosols. Most common are
the Hapludalfs (Gray-Brown Podzolic soils) within the Udalfs
suborder of the Alfisols. Soil pH ranges from slightly alkaline
or neutral to strongly acid.
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Special Uses
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The seeds and buds of rock elm are eaten by deer, rabbits,
squirrels, and a variety of birds. Small mammals such as
chipmunks, ground squirrels, and mice apparently relish the
filbertlike flavor of rock elm seed and frequently eat the major
part of the crop.
Rock elm wood has long been valued for its exceptional strength
and superior quality (3,8). For this reason rock elm has been
drastically overcut in many localities. The wood is stronger,
harder, and stiffer than any of the other commercial species of
elms. It is highly shock resistant and has excellent bending
qualities which make it good for bent parts of furniture, crates
and containers, and a base for veneer. Much of the old-growth was
exported for ship timbers. Currently, the highest quality
sawtimber is found in north-central Wisconsin, lower Michigan,
and southeastern Ontario.
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Vegetative Reproduction
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Rock elm regenerates vegetatively
from root suckers and stump sprouts (10), but vegetative
reproduction in the field is uncommon.
Most elms are considered difficult to root by means of cuttings.
However, leaf-bud cuttings, consisting of leaf blade, axillary
bud, and a shield of stem tissue, treated with a growth hormone
and held under constant mist on a rooting medium of sand or mica,
produced satisfactory results for several species of elm
including rock elm (5).
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Brief Summary
provided by Silvics of North America
Ulmaceae -- Elm family
T. R. Crow
Rock elm (Ulmus thomasii), often called cork elm because
of the irregular thick corky wings on older branches, is a
medium-sized to large tree that grows best on moist loamy soils
in southern Ontario, lower Michigan, and Wisconsin. It may also
be found on dry uplands, especially rocky ridges and limestone
bluffs. On good sites, rock elm may reach 30 m (100 ft) in height
and 300 years of age. It is always associated with other
hardwoods and is a valued lumber tree. The extremely hard, tough
wood is used in general construction and as a veneer base. Many
kinds of wildlife consume the abundant seed crops.
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Distribution
provided by Silvics of North America
Rock elm is most common to the Upper Mississippi Valley and lower
Great Lakes region. The native range includes portions of New
Hampshire, Vermont, New York, and extreme southern Quebec; west
to Ontario, Michigan, northern Minnesota; south to southeastern
South Dakota, northeastern Kansas, and northern Arkansas; and
east to Tennessee, southwestern Virginia, and southwestern
Pennsylvania. Rock elm also grows in northern New Jersey.
-The native range of rock elm.
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Ulmus thomasii
provided by wikipedia EN
Ulmus thomasii, the rock elm[3] or cork elm (or orme liège in Québec), is a deciduous tree native primarily to the Midwestern United States. The tree ranges from southern Ontario and Quebec, south to Tennessee, west to northeastern Kansas, and north to Minnesota.[4]
Etymology
The tree was named in 1902 for David Thomas, an American civil engineer who had first named and described the tree in 1831 as Ulmus racemosa.[5]
Description
Ulmus thomasii grows as a tree from 15–30 m (50–100 ft) tall, and may live for up to 300 years. Where forest-grown, the crown is cylindrical and upright with short branches, and is narrower than most other elms.[6] Rock elm is also unusual among North American elms in that it is often monopodial.[7] The bark is grey-brown and deeply furrowed into scaly, flattened ridges. Many older branches have 3–4 irregular thick corky wings. It is for this reason the rock elm is sometimes called the cork elm.[8]
The leaves are 5–10 cm (2–4 in) long and 2–5 cm (3⁄4–2 in) wide, oval to obovate with a round, symmetrical base and acuminate apex. The leaf surface is shiny dark green, turning bright yellow in autumn; the underside is pubescent. The perfect apetalous, wind-pollinated flowers are red-green and appear in racemes up to 40 mm (2 in) long two weeks before the leaves from March to May, depending on the tree's location. The fruit is a broad ovate samara 13–25 mm (1⁄2–31⁄32 in) long covered with fine hair, notched at the tip, and maturing during May or June to form drooping clusters at the leaf bases.[9]
Although U. thomasii is protandrous, levels of self-pollination remain high.[10]
U. racemosa [:U. thomasii] diagnostic illustration (1865)
U. racemosa [:U. thomasii] diagnostic illustration (1900)
U. thomasii shoot and buds (1920)
U. thomasii new leaves, Meisse
U. thomasii leaves, Sir Harold Hillier Gardens, England
U. thomasii corky twig, Meisse
Ecology
Ulmus thomasii is moderately shade-tolerant.[11] Its preferred habitat is moist but well-drained sandy loam, loam, or silt loam soil, mixed with other hardwoods. However, it also grows on dry uplands, especially on rocky ridges and limestone bluffs.
Pests and diseases
Like most North American elms, U. thomasii is very susceptible to Dutch elm disease.
Cultivation
There are no known cultivars of Ulmus thomasii, nor is it known to be any longer in commerce. It appeared in some US nursery catalogues in the early 20th century.[12][13][14] The species is occasionally grown beyond its native range as a specimen tree in botanical gardens and arboreta, for example in northwestern Europe, but not commonly cultivated in northern Europe, being unsuited to the region's more temperate, maritime climate. However, the tree was propagated and marketed in the UK by the Hillier & Sons nursery, Winchester, Hampshire, from 1965 to 1977, during which time 49 were sold.[15][16]
Ulmus thomasii was crossed experimentally with Japanese elm (U. davidiana var. japonica) at the Arnold Arboretum in Massachusetts, but no clones were released to commerce.[10] Seedlings arising from crossings with Siberian elm (U. pumila) at the Lake States Forestry Experimental Station in the 1950s all perished,[17] a classic case of hybrid lethality.[18]
Notable trees
The US National Champion, measuring 100 ft (30 m) high in 1989, grows in Cass County, Michigan.[19]
Uses
The wood of the rock elm is the hardest and heaviest of all elms, and where forest-grown remains comparatively free of knots and other defects. It is also very strong and takes a high polish, and consequently was once in great demand in America and Europe for a wide range of uses, notably boatbuilding, furniture, agricultural tools, and musical instruments.
Much of the timber's strength is derived from the tight grain arising from the tree's very slow rate of growth, the trunk typically increasing in diameter by less than 2 mm (3⁄32 in) a year. Over 250 annual growth rings were once counted in a log 24 cm (9+1⁄2 in) square being sawn for gunwales in an English boatyard, while a tree once grown at Kew Gardens, London, attained a height of only 12 m (39 ft) in 50 years.[20]
Accessions
- North America
-
Arnold Arboretum, Massachusetts, US. Acc. no. 444-88.
-
Brenton Arboretum, Dallas Center, Iowa, US. No acc. details available.
-
Dominion Arboretum, Ottawa, Canada. No acc. details.
-
Morton Arboretum, Illinois, US. Acc. no. 178-84, wild collected from Reedsville, Wisconsin; 843-2005 (Kelleys Island, Erie County, Ohio); 122-2006 (Dixon County, Nebraska).
-
Nebraska Statewide Arboretum, US. No details available.
- Europe
-
Grange Farm Arboretum, Lincolnshire, UK. Acc. no. 706.
-
National Botanic Garden of Belgium, Meise, Belgium. Acc. no. 19800105.
-
National Botanic Gardens, Ireland,[21] Glasnevin, Ireland. Location: A3 (155)
-
Sir Harold Hillier Gardens, Hampshire, UK. Acc. no. 2008.0419, wild collected in Ontario, Canada, by Kristl Walek
-
Wakehurst Place Garden Wakehurst Place, UK. Acc. no. 1968-48603.
References
-
^ Stritch, L. (2018). "Ulmus thomasii". IUCN Red List of Threatened Species. 2018: e.T61967392A61967401. doi:10.2305/IUCN.UK.2018-1.RLTS.T61967392A61967401.en. Retrieved 18 November 2021.
-
^ "Ulmus thomasii". Tropicos. Missouri Botanical Garden.
-
^ BSBI List 2007 (xls). Botanical Society of Britain and Ireland. Archived from the original (xls) on 2015-06-26. Retrieved 2014-10-17.
-
^ "Ulmus Thomasii Range Map" (PDF). United States Geological Survey. Retrieved 2008-03-02.
-
^ This name had been used in 1800 for a different species of elm, hence the need for the later renaming that honored Thomas.
-
^ Photographs of mature Rock Elm showing narrow profile: Virginia Tech Department of Forest Resources [1], Natural Resources of Canada, tidcf.nrcan.gc.ca [2] Archived 2016-08-02 at the Wayback Machine [3]
-
^ Bean, W. J. (1981). Trees and shrubs hardy in Great Britain, 7th edition. Murray, London.
-
^ Photograph of corky ridges of Rock Elm branches, Michigan State University Plant Encyclopedia [4]
-
^ White, J & More, D. (2003). Trees of Britain & Northern Europe. Cassell's, London.
-
^ a b Hans, A. S. (1981). "Compatibility and Crossability Studies in Ulmus". Silvae Genetica. 30: 4–5.
-
^ "Forestry".
-
^ Kelsey, Frederick W., Choice Trees, cat. 55, N.Y. 1906, p.20
-
^ Griffing's tree & plant book, 1929; Griffing's Interstate Nurseries, C.M. Griffing & Company;p.29
-
^ Griffing's tree & plant book, 1930; Griffing's Interstate Nurseries; p 20
-
^ Hillier & Sons (1977). Catalogue of Trees & Shrubs. Hillier, Ampfield, UK.
-
^ Hillier & Sons Sales inventory 1962 to 1977 (unpublished).
-
^ Sholtz, H. F. (1957). Rock Elm (Ulmus thomasii). Lake States Forest Experimental Station Paper 47:16.
-
^ Mino, Masanobu; Maekawa, Kenji; Ogawa, Ken'Ichi; Yamagishi, Hiroshi; Inoue, Masayoshi (2002). "Cell Death Processes during Expression of Hybrid Lethality in Interspecific F1 Hybrid between Nicotiana gossei Domin and Nicotiana tabacum". Plant Physiology. 130 (4): 1776–1787. doi:10.1104/pp.006023. PMC 166689. PMID 12481061.
-
^ "Rock Elm (Ulmus thomasii)". The 2012 National Register of Big Trees. American Forests. 2012.
-
^ Elwes, H. J. & Henry, A. (1913). The Trees of Great Britain & Ireland. Vol. VII. 1848–1929. Republished 2004 Cambridge University Press, ISBN 978-1-108-06938-0
-
^ "The National Botanic Gardens of Ireland".
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Ulmus thomasii: Brief Summary
provided by wikipedia EN
Ulmus thomasii, the rock elm or cork elm (or orme liège in Québec), is a deciduous tree native primarily to the Midwestern United States. The tree ranges from southern Ontario and Quebec, south to Tennessee, west to northeastern Kansas, and north to Minnesota.
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